Imine Synthesis by Benzylamine Self-Coupling Catalyzed by Cerium-Doped MnO2 under Mild Conditions

Primary amine self-coupling is of significant importance in imine synthesis,yet the thermal catalysis of amine self-coupling normally requires a high temperature or theaddition of expensive oxidants. Herein, Ce-doped MnOxcatalysts were prepared by threedifferent methods, and their surface properties were thoroughly characterized. The Ce-doped MnOxcatalyst obtained by redox-precipitation (CeMn-RO) showed efficientcatalytic performance toward imine synthesis from benzylamine oxidation under mildconditions (80 degrees C, 8 h, air balloon), achieving high benzylamine conversion (92%). Theexceptional oxidative ability of this catalyst could be attributed to its high concentration ofsurface Ce3+,Mn3+, and oxygen vacancies, facilitating the formation of surface oxygenspecies that play a vital role in the reaction. Furthermore, DRIFTS studies were carried outunder the reaction conditions, offering powerful evidence of the benzylamine oxidationmechanism over CeMn-RO